This invention relates to an escalator apparatus and more particularly to a dual-speed escalator apparatus in which the steps on which passengers are conveyed travel at a slower speed at upper and lower landing sections and at a higher speed in an intermediate sloped section.
FIGS. 13 and 14 illustrate a dual-speed moving walk which is disclosed in Japanese Patent Publication No. 61-44795 and which can be applied to an escalator apparatus. In the figures, reference numeral 1 indicates a main frame, 2 indicates an endless step chain movable in an endless circulating path defined on the main frame 1, 2a indicates a dual link assembly including two links 2b pivotally connected at one end to each other by a step axle 2c, the dual link assembly 2a constituting a main component of the step chain 2, and 2d indicates a connecting shaft pivotally connecting the other end of the links 2b remote from the step axle 2c of the neighboring dual link assembly 2a. Reference numeral 3 indicates a series of tread boards each supported by the step axle 2c, and 4 indicates a substantially endless guide rail mounted to the main frame 1 for guiding a guide roller on the connecting shaft 2c. Reference numeral 5 indicates a speed-changing rail disposed on the main frame 1 inside of the guide rail 4 for guiding the roller on the connecting shaft 2d. As best illustrated in FIG. 13, the speed-changing rail 5 is disposed away from and in parallel to the guide rail 4 at the end portions of the main frame 1 to define a low-speed section 5a. The speed-changing rail 5 is slanted toward the guide rail 4 to define a transition or speed-changing section 5b. The speed-changing rail 5 is disposed close to and in parallel to the guide rail 4 in the intermediate section of the main frame 1 to define a high-speed section 5c. Reference numeral 6 indicates a drive unit disposed in the high-speed section 5c of the speed-changing rail 5 in the middle portion of the main frame 1, 6a indicates an endless drive chain driven by the drive unit 6 and having an engaging portion 6b for engaging the connecting shaft 2d, and 7 indicates a passenger conveyed by the tread board 3.
The links 2b of the dual link assembly 2a are arranged to define an angle A therebetween as shown in FIG. 14 throughout the length of the step chain 2, and as the drive unit 6 is rotated clockwise, for example, the drive chain 6a is driven to drive the step chain 2 in the direction of arrow B in FIG. 13 as the engaging portion 6b meshes with the connecting shaft 2d. In the low-speed section 5a at one of the landings of the moving walk, the distance between the guide rail 4 and the speed-changing rail 5 is relatively wide and the angle A between the links 2b of the dual link assembly 2 is small, so the step chain 2 is driven at a low constant speed in this low-speed section 5a. In the speed-changing section 5b, the distance between the guide rail 4 and the speed-changing rail 5 is gradually decreased and the angle A is gradually decreased, so the step chain 2 is accelerated to a higher speed. In the high-speed section 5c, the distance between the rails 4 and 5 is small and the step chain 2 is driven at a high constant speed. As the step chain 2 driven at a high speed in the high-speed section 5c enters into the speed-changing section 5b at the opposite end, the chain 2 is decelerated to a constant low speed at which the step chain 2 is driven in the low-speed section 5a. The step chain 2 is then returned to the starting position through the turn-around section and the return run of the circulating path.
In the above-described conventional dual-speed moving walk, the links 2b of the dual link assembly 2 are in a folded position defining the angle A therebetween even in an high-speed section 5c in which the step chain 2 is engaged by the drive chain 6a. This angle A between the links 2b, which is determined by the distance between the guide rail 4 and the speed-changing rail 5, is not uniform and differs from one dual link assembly to another due, for example, to assembly errors in the guide rail 4. This causes the drive chain 6a to fail to smoothly engage the connecting shaft 2d, generating vibrations and noise. Also, the slidable tread board structure in which the distance between the tread boards is changed by sliding the tread boards relative to each other is difficult to apply to escalators in which the circulating path is sloped.